The term 'REALLY STRANGE' can be summarized by two crossword solutions: EERIE (5 letters) and ODD (3 letters). EERIE is an adjective that describes something as mysterious, spooky, or unearthly. It is often used to describe a feeling of fear or dread. ODD is an adjective that describes something as unusual, strange, or out of the ordinary. Together, these two words describe something as being really strange or unusual.